Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 77: Organic Electronics and Photovoltaics - Transport and Doping

CPP 77.11: Vortrag

Freitag, 16. März 2018, 12:30–12:45, C 243

State of matter dependent charge transfer interactions be-tween planar molecules for doping applications — •Andreas Opitz¹, Paul Beyer¹, Duc Pham¹, Clea Peter¹, Norbert Koch^1,2, Dmitrii Nabok¹, Claudia Draxl¹, Lutz Grubert¹, Stefan Hecht¹, and Caterina Cocchi¹ — ¹Humboldt-Universität zu Berlin, Germany — ²Helmholtz-Zentrum Berlin, Germany

Controlling the electrical conductivity of organic semiconductors is a key requirement for organic electronics, nowadays realized mostly by molecular dopants. Two doping mechanisms, i.e., charge transfer complex (CTC) and ion pair (IPA) formation, have been reported, but their occurrence depending on molecular structure, energy levels, and structure of thin films is elusive. Here, we study the p-type doping of the planar molecule dibenzo-tetrathiafulvalene (DBTTF) as semiconductor, with the planar electron acceptors tetracyano-naphthoquinodimethane (TCNNQ) and hexafluoro-TCNNQ (F6TCNNQ) as dopants. The conductivity increase is stronger for F6TCNNQ than for TCNNQ. Optical spectroscopy reveals the presence of CTCs for DBTTF:TCNNQ blends and CTC and IPA formation for DBTTF:F6TCNNQ blends. We discuss the different fundamental semiconductor-dopant interactions in solution and in solid-state with the aid of energy levels measurements, many-body perturbation theory calculations, absorption and vibrational spectroscopy. The presence of both charge transfer mechanisms in this set of compounds gives us access to their doping efficiency, which is higher for IPA than for CTC formation.